Theoretical physicist here. That comic made me laugh, because it is acutally quite accurate.

See, as a physicist it isn't your job to calculate numbers. A computer or calculator can do this for you, and they are way faster and make no mistakes (unless you tell them to ). It is your job to analyze the deeper structure of the things itself, their dynamics and connections, to find models, formulas and relations characterizing the systems at hand. As such, you are interested patterns. It is intersting to know the magnitude, because the magnitude tells you something about competing scales.

For example if you want to compute the movement of the sun around the orbit, gravitational effects on (roughly) the same scale are interesting. This applies the sun, or too an lesser extend even the moon. Both influence the track of the earth in its orbit significantly. But obviously you can neglect effects on a lower scale (for example a single human spinning around its own axis, influencing the angular momentum of the planet). So it is nice to know if the number you are looking at is ~ 10 or ~ 100 or ~ 1000, but not if its 8, 13 or 5. For a theoretical physicist, the gravitational law looks like F ~ m1* m2 * 1/r^2. No one cares for the constant accompanying . In this context, i also saw people writing pi = 1 (though most of the time, pi is kept, because it tells you something about the structure of a formula).

It is very much the same with shapes. A rectangular and a circle are topological pretty much the same. Assuming that you don't make a large error replacing one with another, most of the time you do this, if it is easier to calculate.